This project addresses the critical need for real time quantification of fetal hypoxia, a condition of concern during all births that can lead to brain damage or death. Currently, no such direct monitor of hypoxia exists. A membrane covered polarographic oxygen sensor with a heater for arterialization of the scalp capillary blood will be designed. Also included on the contacting probe will be a thermistor to measure the local blood perfusion rate, indicating both the basal scalp perfusion level as well as the level of arterialization of the capillary blood. This thermistor will use protocols adapted from the Enhanced Thermal Diffusion Probe (ETDP), Thermal Technologies' first product, to measure temperature (0.0035 degrees C) and perfusion (10% over the range of physiologic flows). The basal blood perfusion rate is measured when the polarographic heater is not on, and the degree of arterialization of the local blood is indicated by the increase in local perfusion when the polarographic he;iter is on. Tile pressure sensitivity of the polarographic oxygen sensor (0.1 mmHg resolution, 0.1 mmhg accuracy) will be eliminated through a proprietary Bilayer Membrane to be developed during Phase 1. This membrane will also reduce operator specific calibration variability. The current-to-voltage amplification circuit for the polarographic current will be located near the sensor to provide noise immunity. Following successful demonstration of feasibility during Phase 1, Phase 11 will be devoted to pre-commercial development and evaluation of the integrated system by our Clinical Evaluation Group.